Correlation between immunity from BCG and the morbidity and mortality of COVID-19
Dakshitha Wickramasinghe, Nilanka Wickramasinghe, Sohan Anjana Kamburugamuwa, Carukshi Arambepola, Dharmabandhu Nandadeva Samarasekera
Abstract
Abstract Background To investigate the association between parameters indicating immunity from BCG at country level (presence of BCG vaccination policy, BCG coverage, age-specific incidence of tuberculosis (TB)) and the morbidity and mortality of COVID-19. Methods Country-specific data for COVID-19 cases and deaths, demographic details, BCG coverage and policy, age-specific TB incidence and income level were obtained. The crude COVID-19 cases and deaths per 100,000 population were calculated and assessed against the parameters indicating immunity from BCG using linear regression analysis. Results Univariate analysis identified higher income level of a country to be significantly associated with COVID-19 cases ( p < 0.0001) and deaths ( p < 0.0001) but not with its case fatality rate. The association between COVID-19 and TB was strongest for TB incidence in patients > 65-years (Cases (r s = − 0.785, p = 0.0001)) and deaths (r s = − 0.647, p = 0.0001). Multivariate analysis identified the higher income level of a country and not having a universal BCG vaccination policy to affect the COVID-19 cases. The deaths were inversely affected by the presence of BCG vaccination policy and coverage; and positively by the TB incidence in patients > 65-years. Conclusion Significant inverse correlations observed between cases and deaths of COVID-19 and BCG related parameters highlights immunity from BCG as a likely explanation for the variation in COVID-19 across countries.